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Thibaut Schaeffer

PROFILE

Thibaut Schaeffer

Thibaut Schaeffer engineered core systems for the powdr-labs/powdr repository, focusing on modular backend development, constraint-solving, and performance optimization. He delivered features such as GPU-ready trace generation, multi-ISA OpenVM integration, and scalable autoprecompile frameworks, using Rust and CUDA to enable efficient, extensible runtime execution. His work included refactoring constraint solvers for algebraic clarity, streamlining CI/CD pipelines, and enhancing data structures for deterministic, high-throughput processing. By consolidating architectural patterns and introducing robust abstractions, Thibaut improved maintainability and reliability, addressing complex problems in zero-knowledge proof systems and virtual machine design with a deep, systems-level technical approach.

Overall Statistics

Feature vs Bugs

81%Features

Repository Contributions

148Total
Bugs
14
Commits
148
Features
61
Lines of code
89,114
Activity Months19

Work History

April 2026

1 Commits • 1 Features

Apr 1, 2026

April 2026 — Key feature delivery and impact for succinctlabs/sp1. Delivered ZeroCheck Data Structure Capacity Expansion, increasing the data structure capacity to accommodate more columns and upgrading numeric types from 32-bit to 64-bit. This enables larger datasets, more robust data validation, and improved scalability for data-heavy workloads. The change improves throughput and reliability in data validation scenarios and sets the foundation for future analytics capabilities. The work is captured in commit 911a4b4b31773dc9f5460259bc9efcf96399fefb, co-authored by qwang98 and Georg Wiese.

March 2026

12 Commits • 4 Features

Mar 1, 2026

March 2026 delivered foundational multi-ISA OpenVm capabilities and key runtime improvements. Implemented ISA-agnostic OpenVm through the OpenVmISA trait and a generic powdr-openvm, refactored PowdrAir into SymbolicMachine to consolidate architecture for robustness, and introduced unconditional superblocks for improved non-sequential execution. Also streamlined bus/memory paths, generalized timestamp handling, and completed CI/readability enhancements. Stabilized runtime by addressing executor-wrapping issues and segmentation faults with safer handling paths and targeted unsafe write usage.

February 2026

3 Commits • 1 Features

Feb 1, 2026

February 2026: Delivered a targeted codebase refactor for powdr to improve performance, modularity, and maintainability. Consolidated execution state-based overlap analysis by removing the Snapshot trait and deriving instret/global_clk from the execution state, enabling faster candidate evaluation. Generalized instruction handling by moving is_branching and is_allowed to the Adapter trait, resulting in an agnostic, extensible instruction pathway. Simplified the execution bus optimizer by adopting constraints in place of substitutions, reducing complexity and improving clarity of optimization decisions. These changes establish a robust foundation for integrating new adapters and future performance improvements, with minimal disruption to external interfaces.

January 2026

4 Commits • 2 Features

Jan 1, 2026

January 2026 monthly summary for powdr-labs/powdr focused on delivering measurable improvements to the Autoprecompile (APC) system and execution state, with an emphasis on reliability, analytics, and maintainability that drive business value for performance-critical workloads.

December 2025

5 Commits • 2 Features

Dec 1, 2025

December 2025 (powdr-labs/powdr): Focused on strengthening correctness and maintainability of the runtime by delivering runtime verification for optimistic constraints and targeted code quality improvements. The work reduces risk of incorrect optimizations, improves performance, and lowers future maintenance cost by introducing robust abstractions and adapters.

November 2025

6 Commits • 3 Features

Nov 1, 2025

November 2025 focused on reducing architectural complexity, improving CI reliability, and enhancing observability. In powdr, modernization removed the legacy Plonk path, encapsulated GPU bus IDs within periphery instances, and simplified compilation by inlining ElfProgram into OriginalProgram, resulting in leaner code and faster builds. CI and automation were strengthened by centralizing benchmark fetching/patching into a single GitHub Action and expanding PR test coverage across multiple runners with a dedicated testing initialization action, improving reliability and feedback speed. In openvm Stark backend, added an Air ID to trace metrics to differentiate multiple instances of the same air type, improving clarity and usability of metrics. These changes reduce maintenance burden, shorten iteration cycles, and improve observability, delivering measurable business value across build times, reliability, and data-driven debugging.

October 2025

7 Commits • 2 Features

Oct 1, 2025

October 2025 monthly summary focusing on delivering business value through GPU-ready trace processing, API surface improvements, and build reliability fixes across powdr and openvm. Key outcomes include GPU-optimized trace generation, safer APC-derived/original column handling, and a streamlined Executor API bound, resulting in faster processing, fewer build-time issues, and cleaner interfaces for future work.

September 2025

10 Commits • 3 Features

Sep 1, 2025

September 2025 performance summary for powdr-labs/powdr. Focused on architecture modernization and performance improvements across constraint solving, evaluator/bus interactions, and API/dependency hygiene. Delivered a robust, modular solver, a lower-allocation evaluation path, and a cleaned API surface with synchronized dependencies, enabling faster delivery of features and greater stability. Business value includes improved throughput for optimization workloads, reduced maintenance costs, and easier onboarding.

August 2025

3 Commits • 3 Features

Aug 1, 2025

Powdr engineering monthly summary for 2025-08: Delivered modular extensibility and data handling improvements that enable flexible performance optimization, safer solver evolution, and robust data interchange. Key work focused on three deliverables with direct business value: extensible autoprecompiles framework with pluggable PGO adapters, algebraic constraint type to replace generic solver scaffolding, and serde support for ApcWithStats for persistence and networking.

July 2025

25 Commits • 7 Features

Jul 1, 2025

In July 2025, delivered substantial modularization, performance, and reliability improvements across powdr/powdr. Key features include migrating APC functionality into a dedicated APC crate with data generation/persistence, PC data structure hardening, and PGO enhancements using full profiling data. Also improved OpenVM integration and opcode handling, refined RV64 label detection, and enhancements to instruction treatment. Infrastructure cleanups improved CI/PGO performance and maintainability.

June 2025

24 Commits • 9 Features

Jun 1, 2025

June 2025 – Powdr project (powdr-labs/powdr): Key business-impact deliveries across runtime integration, performance, and maintainability. Focus areas included OpenVM integration with Stark backend alignment, APC generation optimizations, and codebase hygiene, with targeted performance tuning and bug fixes. Key highlights: - OpenVM integration and backend alignment: Associate OpenVM type, update Stark backend, and relocate default bus map for safer interaction. - APC enhancements: Parallel APC generation, refactored bus map retrieval, extraction of bus map from SDK config, and shared dummy periphery across APCs to reduce setup time and improve scalability. - Witgen reliability and performance: Fix timestamp LT checks that caused unnecessary memory interaction issues; disable regmem Witgen acceleration in favor of original program cloning to preserve safety while improving performance. - Workspace hygiene and API cleanup: Move dependencies to the workspace, collect used instructions into a hashset, make blacklist public, and reexport degree bound for cleaner interfaces. - PGO relocation and cost tuning: Move PGO type to the OpenVM crate and tune the PGO cost function with a hard column count limit to stabilize performance. Additional notes: Other improvements included API and customization cleanup, air retrieval/allowlist improvements, and related refactors to support safer, faster, and more maintainable code paths.

May 2025

12 Commits • 6 Features

May 1, 2025

May 2025 performance summary for powdr-labs/powdr. Delivered foundational OpenVM integration scaffolding and dependencies upgrades to enable OpenVM-based workflows, trimmed the backend surface by removing deprecated eSTARK and Halo2 backends, and hardened CI and workspace tooling for more reliable nightly tests. Also delivered APC module refactor with a builder pattern for precompile generation, optimized PowdrAir trace generation, and exposed ELF loading APIs for reuse in RISCV/OpenVM components. Collectively these changes reduced maintenance burden, accelerated feature delivery, and strengthened the platform for future OpenVM initiatives.

April 2025

1 Commits • 1 Features

Apr 1, 2025

April 2025 (powdr-labs/powdr): Focused on performance-oriented optimization of the PIL optimizer. Implemented PIL Optimizer Efficiency Enhancements to reduce waste by avoiding materialization of columns constrained to non-shifted multilinear polynomials through replacing linear constraints with intermediate polynomials. This work impacted AST analysis, mock backend, STWO circuit builder, STWO prover, PIL analyzer, and the PIL optimizer, and included extensive test coverage. The featured commit is Linear constraint remover (#2425) with hash 2cb45482834a8f49bcec8c4f2b7c70f9cc5bc8e7. End-to-end changes across the stack reinforce maintainability and pave the way for improved throughput and scalability of PIL optimization.

March 2025

3 Commits • 3 Features

Mar 1, 2025

March 2025: Delivered three core enhancements in powdr: 1) VM Code Generation Optimization and Main VM Dispatcher Skip; 2) CI/CD Pipeline Simplification and Mock Prover Adoption; 3) PublicDeclaration Structure Simplification. These changes reduce VM startup/dispatch overhead, shorten CI cycles with deterministic tests, and simplify data models. While no explicit bug fixes documented, the work improves reliability and maintainability. Technologies showcased include VM codegen, ROM/PC/return handling improvements, CI/CD modernization, mock prover integration, and data-model simplification.

February 2025

3 Commits • 2 Features

Feb 1, 2025

February 2025 performance summary for powdr-labs/powdr focusing on delivering high-impact features, fixing critical correctness issues, and strengthening the JIT-ready arithmetic foundation. Key business outcomes: - Slimmer interaction identifiers reduce memory footprint and data transfer costs across bus interactions, enabling more scalable state tracking. - JIT-ready arithmetic foundation accelerates future runtime code generation and optimizes cryptographic/VM-related workloads. - Improvements align with witgen expectations, ensuring more robust, maintainable code and repeatable builds.

January 2025

9 Commits • 3 Features

Jan 1, 2025

January 2025 monthly summary for powdr-labs/powdr focusing on bus interaction, algebraic analysis, and mock prover correctness. Delivered features and bug fixes that strengthen verification paths, reduce edge‑case risk, and improve maintainability across the verification stack.

December 2024

7 Commits • 2 Features

Dec 1, 2024

December 2024 Powdr monthly summary: Delivered end-to-end CI enhancements, deterministic data handling, ROM generation stability, and an efficiency-focused optimization pass, driving measurable business value through faster feedback loops, reproducible builds, and cleaner code paths. The work aligns CI benchmarks with the book deployment workflow and improves overall product reliability.

November 2024

10 Commits • 5 Features

Nov 1, 2024

November 2024 Monthly Summary for powdr-labs/powdr: Focused on delivering value through robust features, reliability improvements, and maintainability enhancements. The work this month reinforced the product's capability in witness generation, tightening of test and build pipelines, and clearer debugging visibility, while consolidating standards across the workspace.

October 2024

3 Commits • 2 Features

Oct 1, 2024

October 2024 — Focus on developer experience and build configurability for powdr. Delivered a documentation overhaul including plonky3 backend guidance, added degree parameterization for submachines to enable finer control during compilation, and fixed a bootloader comment typo to reduce confusion. These changes improve onboarding, reduce maintenance overhead, and set the stage for future optimization.

Activity

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Quality Metrics

Correctness90.0%
Maintainability88.8%
Architecture88.6%
Performance83.0%
AI Usage22.4%

Skills & Technologies

Programming Languages

AssemblyBashC++JSONJavaScriptMarkdownPythonRustShellTOML

Technical Skills

API DesignAPI developmentAST ManipulationAST manipulationAbstract Syntax Tree (AST) ManipulationAbstract Syntax TreesAbstract Syntax Trees (AST)AbstractionAlgorithm DesignArithmetic CircuitsAssembly LanguageAssociated TypesBackend DevelopmentBash scriptingBenchmarking

Repositories Contributed To

4 repos

Overview of all repositories you've contributed to across your timeline

powdr-labs/powdr

Oct 2024 Mar 2026
18 Months active

Languages Used

AssemblyMarkdownRustTOMLYAMLJavaScriptPythonShell

Technical Skills

Assembly LanguageCode CorrectionCompiler DevelopmentDocumentationRustRust Programming

openvm-org/openvm

Oct 2025 Oct 2025
1 Month active

Languages Used

Rust

Technical Skills

ConcurrencyRustSystem Programming

openvm-org/stark-backend

Nov 2025 Nov 2025
1 Month active

Languages Used

Rust

Technical Skills

backend developmentdata serializationmetrics tracking

succinctlabs/sp1

Apr 2026 Apr 2026
1 Month active

Languages Used

C++Rust

Technical Skills

CUDAData StructuresGPU Programming